os/bluestore: Fix using 'near' hint in cache

We can now get near hint that refers to buffer that is in writing state.
Such buffer is not in cache yet and cannot provide in-queue location.
We only extact cache_private.

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index bb6474de3112c562b4484029c95e38492a2a3da2..5a3c0d70e2e32510cd2ab0357c34c3f819a59359 100644 (file)
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -1203,7 +1203,7 @@ struct LruBufferCacheShard : public BlueStore::BufferCacheShard {
   explicit LruBufferCacheShard(BlueStore* store) : BlueStore::BufferCacheShard(store) {}
 
   void _add(BlueStore::Buffer *b, int level, BlueStore::Buffer *near) override {
-    if (near) {
+    if (near && !near->is_writing()) {
       auto q = lru.iterator_to(*near);
       lru.insert(q, *b);
     } else if (level > 0) {
@@ -1328,8 +1328,12 @@ public:
     dout(20) << __func__ << " level " << level << " near " << near
              << " on " << *b
              << " which has cache_private " << b->cache_private << dendl;
+    ceph_assert(ceph_mutex_is_locked(cache));  // see _txc_finish_io
+    ceph_assert(b->is_clean() || b->is_empty());
     if (near) {
       b->cache_private = near->cache_private;
+    }
+    if (near && !near->is_writing()) {
       switch (b->cache_private) {
       case BUFFER_WARM_IN:
         warm_in.insert(warm_in.iterator_to(*near), *b);
@@ -1344,17 +1348,18 @@ public:
       default:
         ceph_abort_msg("bad cache_private");
       }
-    } else if (b->cache_private == BUFFER_NEW) {
-      b->cache_private = BUFFER_WARM_IN;
-      if (level > 0) {
-        warm_in.push_front(*b);
-      } else {
-        // take caller hint to start at the back of the warm queue
-        warm_in.push_back(*b);
-      }
     } else {
       // we got a hint from discard
       switch (b->cache_private) {
+      case BUFFER_NEW:
+        b->cache_private = BUFFER_WARM_IN;
+        if (level > 0) {
+          warm_in.push_front(*b);
+        } else {
+          // take caller hint to start at the back of the warm queue
+          warm_in.push_back(*b);
+        }
+        break;
       case BUFFER_WARM_IN:
         // stay in warm_in.  move to front, even though 2Q doesn't actually
         // do this.
@@ -1665,6 +1670,8 @@ void BlueStore::BufferSpace::_add_buffer(BufferCacheShard* cache,
   ldout(cache->cct, 20) << __func__ << "? " << b << dendl;
   cache->_audit("_add_buffer start");
   ceph_assert(!b->set_item.is_linked());
+  // illegal to provide both near and cache_private
+  ceph_assert(!(near && cache_private != 0));
   bool add_to_map = true;
   if (b->is_writing()) {
     ceph_assert(b->txc);